Means fob defrosting cooling ele



Sg t. 1, 1936. J. A. DIENNER ET AL MEANS FOR DEFROSTING COOLING ELEMENTMECHANICAL REFRIGERATORS Original Filed Au 22, 1927 Reicsued Sept. 1,1936 MEANS, FOR DEFBOS TING COOLING ELE- MENT OF'MECHANICALREFRIGEBATQRS John A. Dienner, Evanston, and John E. Gardner, Chicago,Ill., assignors to Richard Ford, Detroit, Mich.

Original No. 4,942,412, dated January 9, 19:4, Serial No. 214,490,August 22, I927. Application for reissue January 7. 1935, Serial No, 738

24Clalml.

Our invention relates in general to mechanical refrigerators and moreparticularly to means for defrosting the cooling element of suchrefrigerators.

In mechanical refrigerators it has always been a great problem toprevent frosting as much as possible in order to maintain the operatingefliciency of the device. When frost collects on the cooling element ofa mechanical refrigerator, as it does very quickly from the moisturein'the air,

an insulating coating of ice is formed over the cooling element. Thiscoating of insulation on the cooling element of: the refrigerator meansthat mechanical equipment, whereby the refrigerating action is broughtabout, must necessarily operate a great deal oftener and longer in orderto maintain the refrigerator at its desired tem-' having therefrigerator shut it down manually so that it will no longer respond tothe thermostatic 30 control device in the refrigerator. The lowtemperature of the refrigerator is then maintained by the melting of thefrost or insulating ice coating. After this coating has melted entirelyaway it is again necessary to manually reconnect the 35 mechanicalrefrigerating apparatus. Under'this procedure, there is great danger ofthe home owner forgetting to reconnect the refrigerator at the propertime, or being unable to do so. .Under these conditions therefrigerating compartment 40 of the refrigerator is not maintained atits proper temperature and the food thatit is desired to preserve withinthe device is very likely to be spoiled. 7

The principal object of our invention is to overcome all the abovedifliculties by providing means for automatically. bringing about thisde frosting operation which needs no attention from the refrigeratoroperator or home owner 50 whatsoever.

Another object of our invention is to provide means responsive to theformation of an insulating ice coating about the cooling element.

Another object is to provide means controlled 55 by this device which isresponsive to the frosting in conjunction with the accompanying drawing.10

In practicing our invention we provide athermal element which isresponsive directly to the temperature of the refrigerating or coolingelement and we also provide a thermal element .which is responsive tothe temperature of the 15 refrigerating cabinet proper. 7 Means areprovided for automatically opening the circuit of the motor controllingthe electric compressor, where such compressor is used to provide therefrigeration, when the temperature within the cooling device proper isbelow the temperature of the refrigerator. A thermally controlled switchis also employed for automatically operating the refrigerating mechanismunder normal conditions, but

its oper'ation'is without effect if an insulating frosting is present onthe outside of the cooling element for the reasons above stated.

While in the drawing we have shown our invention' applied to an electric type of refrigerator, it will be understood from the drawing anddescription how the same principle may be employed in any mechanicalrefrigerator to perform the same-functions.

It will be appreciated that while we have shown a more or lessdiagrammatic view ofthevarious elements of an electric mechanicalrefrigerator that they may be of any well' known or suit-- able typ Inthe drawing, we have shown a sectional view of an electric mechanicalrefrigerator with cer- 40' pressor 5 to the cooling or condensing coil8-60 through the pipe 1 and the expansion valve 8 through the coolingcoils, (not shown) in, the brine tank 9, and thencebackto the compressorthrough the pipe Ill. The condensing coil 6 may be cooled in anysuitable or well known manner.

brine tank II. The reason for this provision, 1

whereby the thermoresponsive element 13 controlling the fluid whichoperates the thermostat II is immersed in a small brine tank, is torender its action somewhat sluggish so that momentary opening of thedoor leading to the refrigerating compartment 1 of the refrigerator Iwill not bring about intermittent operation of the electric motor I andthe compressor unit I. I

The circuit of the electric motor is also controlled by a snap switchIi, which may be of any well known or suitable construction. This snapswitch is controlled by two bellows l6 and I1.

The bellows I8 is controlled through the medium of a fluid acting in thepipe I8 from the thermoresponsive element is immersed in the brine tank8 adjacent to the regular cooling coils of the refrigerator. The bellowsI! controlling the actlon of the snap switch It is thus directlyresponsive to the temperature maintained by the cooling coils within thebrine tank, which is unaffected by the coating of frost or insulatingice that forms about the outside of the brine tank under and aroimd thedrawers II, and 22, for example, associated with the brine tank underusual operating conditions.

The snap switch II is also controlled by a bellows I! which is operatedby a fluid acting in the pipe II This fluid is controlled by the thermalelement 24 which is immersed in a small brine tank ii in the same mannerthat the element I3 is immersed in a small brine tank ll and for thesame reasons. Obviously these two brine tanks may be combined. Thebellows "is thus controlled and is directly responsive to thetemperature maintained in the refrigerating compartment 2 of therefrigerator. The snap switch I! which is adapted to be operated by theconjoint action of the bellows I! and I1 is adapted to open its contacts26 when the temperature of the brine solution is a predetermined amountbelow the temperature of the refrigerating compartment of therefrigerator. This is indicated diagrammati- 'cally in the drawing wherea contraction of the fluid in the bellows I 0 causes the movement of theelement 11 about its pivot 2| in a downward direction, while a rise intemperature in the refrigerating. compartment tends to expand thebellows l1, thereby bringing about the opening movement of the contactmahng member I. I

So long as the proper temperature differential is maintained between thebrine tank 9 and the thermal element 20 the action of the bellows I. andI1 counterbalance each other and the operation of the refrigerator isdirectly controlleiby the thermostat switch II in any usual or wellknown manner. That is, so long as there is no appreciable coating offrost or ice on the outside of the brine tank, the action of therefrigerator proceeds in any usual or well known manner underthe-control of the thermostat switch ll, so that the proper temperatureis maintained within the refrigerating compartment 2. However, as soonas there is a thick enough insulating coating of frost or ice on theoutside of the brine tank, the ready transfer of heat from therefrigerating compartment to the cooling element ing compartment therequisite amount.

in the brine. tank 3 is retardedand'inhibited.

, The mechanical refrigerating equipment comprising the motor 4 and thecompressor 5 is thus maintained in operation to still further reduce thetemperature of thebrine tank in an attempt to reduce the temperaturewithin-the refrigerat- This brings about a differential action betweenthe bellows I8 and the bellows l'l controlling the "thermostat switchl5. when a predetermined difierential is reached the contact makingmember 28 of the thermostat switch I! is moved away from its associatedcontact member and the circult of the compressor and the motor ispermanentLv opened irrespective of the position of the thermostaticswitch H, controlling the normal operation of the refrigerator. Thetemperature within the refrigerating compartment 2 of the refrigeratoris then maintained by the meltin of the coating of ice or frost on thebrine tank, since the mechanical refrigerating equipment can no longerbe operated. When the ice and frost is melted away the temperature ofthe brine tank rises' and the bellows l6 expands. Under these conditionsthere is no longer a differential in temperature between the brine tank9 and the refrigerating compartment I and there is no differentialbetween the bellows l8 and the bellows ll, consequently the contactmaking member 2| is brought into engagement with its associated contactmember and the circuit of the thermostatswltch H and the operation ofthe refrigerating system proceeds as before. The

well known manner. The predetermined diiferential in temperaturegoverning the operation of the bellows II and I1 controlling the snapswitch ll may be brought about by the adjustment of the follow-throughof the contact member as-- sociated with the contact making member 20.

The operation of the refrigerator now proceeds, as before, under thecontrol of the thermostatic snap switch If until another insulatingcoating of frost or ice, sumcient to bring about the requiredtemperature differential is formed, when the same operations arerepeated. From the foregoing, it will be seen that we have providedmeans for automatically bringing about the defrosting of the coolingelement of a mechanical refrigerator. By our invention the frost or iceis caused to melt to remove the insulating coating and to permit the icedrawers 2|, 2| and i! to become readily accessible In addition, ourinvention provides means for preventing the unnecessary movement of themechanical refrigerating equipment with its consequent wear and tear onthe apparatus in addition to the usual use of power in a vain attempt tomaintain the required temperature within the refrigerating compartment.Also, our invention provides means for automatically initiating-theoperation of? the mechanical refrigerating equipment as soon as thefrost or ice condition is removed so as to continuously maintain thetemperature within the refrigerating compartment at the proper degree.

It will be understood that the differential control element l5comprising the interacting bellows It and I1 may be also employed tocontrol a valve governing a gas operated refrigerator or, in fact, anytype of mechanical refrigerator in a manner that will be obvious fromdescription.

While we have shown and described one embodiment of our invention, weare aware that many changes, modifications and deviations may be made,as it will be understood that we desire to protect by Letters Patent allsuch changes, modifications, deviations as come within the scope of theappended claims.

We claim:

1. In a refrigerator, 9. refrigerating compartment and a cooling elementassociated with said compartment, mechanically operated means forlowering the temperature of said cooling element, a thermal responsivedevice responsive to the temperature of said cooling element, and athermal responsive deviceresponsive to the temperature the foregoing ofsaid compartment, and means for controlling said mechanical. means inaccordance with the temperature differential between said thermalresponsive devices.

2. A refrigerator comprising the combination of means providing arefrigerating compartment,

a cooling element within the compartment, means for driving a fluidtherethrough, and tempera-'- ture responsive means operative wheneverthe difference between the temperature of the cooling-element and thetemperature in the refrig-' erating compartment reaches a' predeterminedvalue for stopping the fluid driving means. 3. A refrigerator comprisingthe combination of a refrigerating compartment, cooling means to coolsaid compartment, mechanical means to lower the temperature of saidcooling means, and means to automatically control the mechanical meansin accordance with the difference of temperature between the compartmentand the cooling means.

4. A refrigerator comprising the combination of a refrigeratingcompartment, cooling means to cool said compartment, mechanical means tolower the temperature of said cooling means, means to automaticallycontrol the mechanical means in accordance with the difference oftemperature be- 7 tween the compartment and the cooling means,

and means acting serially with said automatic means to control themechanical means in accordance with the temperature of said compartment.

5. In combination, a cooling chamber having a fluid expansion member forextracting 'heat from said chamber, a compressor for compressing fluidfor said member, and thermally controlled -means subject to thedifference in temperature between the chamber and the member forpreventing the operation of said compressor.

6. In combination, a cooling chamber having a fluid expansion cooleddevice for extracting heat from said chamber, means for compressingfluid for expansion to cool said device thermally controlled meanssubject to the difl'erence in temperature between the chamber and thedevice for preventing the operation of said means, and thermallyactuated means for controlling the temperature in said chamber.

'1, In combinatioma fluid containing chamber, a heat exchange device forabsorbing heat from the fluid in the chamber, means for passing acooling fluid through the heat exchange device to carry heat away fromsaid device, a control device for said last named means and meansresponsive to a differencein temperature between the fluid in thechamber and the heat exchange device for actuating said control'device.

8. In combination, a refrigerating chamber, a

mechanical refrigerating comprising a heat exchange device for coolingthe chamber,

' an electric motor for operating the system, thermally controlled meansfor stopping and starting the motor in response to absolute temperaturein the chamber, said last named means including a switch in the circuitof the motor, and thermally controlled means having a part in heatconducting relation to the heat exchange device and a a part in heatconducting relation. to the air in the cooling chamber for interruptingthe circuit of the motor, said last named means comprising a switch inseries relation to the aforesaid switch.

9. In combination, a cooling chamber, a heat exchange device forextracting heat from said chamber, a motor for operating said device, athermally actuated switch in said chamber for controlling said motor,and means disposed in said chamber away from said switch for retardingthe action of said switch. 1 Y

10. In combination, acooling chamber, a heat exchange device forextracting heat from said chamber, a motor for controlling said device,

thermally actuated means responsive to the temperature in said chamberfor actuating said motor, secondary means responsive to the differencein temperature of .said chamber and said device for actuating said motorindependently of said first named actuating means, and means in saidchamber for retarding'the action of said thermally actuated means.

11. In combination, a cooling chamber, fluid heat exchange means forextracting heat from said chamber, means for controlling the flow offluid through said heat exchange means, differential thermally actuatedmeans responsive to the temperatures of said heat exchange means and ofsaid chamber for rendering said fluid flow controlling means imperative,and means in said chamber for retarding the action of said thermallyactuated means.

12. In combination, a refrigerating system ineluding a cooling chamberand a heat exchange device, means responsive to the temperature of saidchamber for controlling the operation of said system, differential meansserially connected with said responsive means for maintaining apredetermined temperature difference between said cooling chamber andsaid heat exchange device, and means in said chamber for retarding theaction of said responsive means.

13. In combination, a cooling chamber, a heat exchange device forextracting heat therefrom, differential means responsive to thetemperature in said chamber and in said heat exchange device formaintaining a predetermined temperature relation therebetween, and meansresponsive to the temperature in said chamber for maintaining apredetermined temperature in said chamber, said differential means andsaid last named means being connected in series relation.

14. In combination, a cooling chamber, a heat exchange device forextracting heat therefrom, differential control means responsive tothetemperatures of said chamber and said heat exchange device formaintaining a predetermined temperature relation therebetween, andthermally sensitive means responsive to the absolute temperature in saidchamber for controlling the temperature in said chamber.

15. In combination, a cooling chamber, a heat exchange device forextracting heat therefrom, differential control means responsive to thetemperatures of said chamber and said heat exchange device formaintaining a predetermined tem- .10 temperature difference between saidchambers,

and means responsive only to the temperature a heat dissipating deviceand a heat extracting.

tive means responsive. to the absolute temperature in said chamber forcontrolling the temperature in said chamber, and means for retarding theaction of said thermally sensitive means.

16. In combination, a pair of chambers, means for extracting heat fromsaid chambers, means responsive to the temperature in each of said achambers for differentially controlling said heat extracting means tomaintain a predetermined in one of said. chambers for controlling theabsolute temperature in said chamber.

17. The method of defrosting the heat extracting device of arefrigerating system employing device which consists in normallycontrolling the refrigerating system by starting and stopping thedissipation of heat by the heat dissipator, and

[without reference to said normal control stopping the dissipation ofheat by said heat disipating device in response to an accumulation offrost on said heat absorbing device, and starting the dissipation ofheat by said heat dissipation device only in response to a rise intemperature of the heat extracting device to a point above the freezingpoint of water.

18. A refrigerating system comprising in combination a heat extractingdevice which is subiect to moisture-laden atmosphere, and a heatdissipating device operatively connected with said extracting device,thermally responsive means for normally stopping and starting the heatdissipating device, said extracting device being operated atatemperature at which frost accumulates thereupon, and means responsiveto accumulation of frost on the evaporator for rendering the heatdissipating device ineffective, said last named means being responsiveto a temperature condition of the heat extracting device above 32 F. forrestoring the system to the control of said normally controllingthermally responsive means.

19. In a refrigerator controlling and defrosting system, having a heatextracting device subiect to moisture-laden air, a heatdissipatingdevice, an electric circuit for controlling the operation ofsaid heat dissipating device, the combination of a pair of thermostatssubject to the action of said extracting device for controlling saidcircuit to defrost the heat extracting device,

one of said thermostats being in fixed heat eon-' ducting relation tothe heat extracting device, and the heat conducting relation of theother one of said thermostats to the heat extracting device beingsubject to the formationof a coat-' ao,oav' perature relationtherebetween, thermally sensitracting device operated thereby, whichcomprises normally stopping the heat dissipating device re-' sponsive tothe attainment of a predetermined low temperature in the space to berefrigerated, and starting the heat dissipating device'responsive to theattainment of apredetermined high temperature-in said space, andindependently of the temperature in said space stopping the heat.

dissipating device responsive to a predetermined decrease in heatextracting ability of said heat extracting device.

21. In combination, a cooling chamber, a heat extracting device forextracting heat from said chamber, a heat-dissipating device forremoving heat from said extracting device, normally controllingthermostatic means responsive to variations in absolute temperature insaid chamber for stopping and starting said dissipating device, and

thermostatic means responsive to changes in-the thermal drop betweensaid extracting device and the air in said chamber due to theaccumulation of frost on the extracting device for rendering said heatextracting device ineffective.

22. In a refrigerator temperature controlling and defrosting system, arefrigerating chamber,

a heat extracting device therefor, a, heat dissipating device, automaticmeans controlling the normal cycle of rise and fall of temperature "insaid chamber by causing intermittent operation of saldheat dissipatingdevice to maintain a mean desired-temperature, and automatic meansgoverned by the formation of a coating of frost upon said heatextracting device for rendering said first automatic means ineflective.

23. Method of controlling the rate of heat extraction by a heatextracting device and a heat dissipating device from a refrigeratorchamber. which comprises normally periodically operating the heatdissipating device in response to heat inflow to the chamber to reducethe temperature by flow of heat from the chamber to the heat extractingdevice until frost is deposited upon the heat extracting device, and inresponse to the diminution in the flow of heat from the chamber to theextracting device by said deposit of frost permitting the heat toaccumulate by not extracting it until the deposit of frost has beenmelted thereby, and thereupon resuming the normal periodical operationof the dissipating device.

24. In a refrigerating system employing a. heat extractor and a heatdissipator in which moisture from the air condenses and freezes on theheat extractor during the normal operation of the system, the methodofdefrosting the heat extractor which consists in initiating the start ofa modified operation of the system in response to the accumulation offrost on the heat extractor JOHN A. nmmm was a. 0mm.

